Statistical efficiency in bull progeny testing for calving difficulty

Abstract

The binomial distribution was used to examine the precision attainable in bull progeny testing for traits like calving difficulty as the following parameters were varied: Po, the basic incidence level in the population, n, the progeny group size, and α and β, the probabilities of two kinds of erroneous conclusion. The results showed that in all circumstances a group size of 250–300 progeny gave a good compromise between cost and precision. There was little to choose between testing based on calvings in heifers and in cows. As the basic frequency increases, more progeny are required for a given degree of precision. Thus testing is more expensive in breeds with high rates of difficult calving than in those with low rates.